Technical Discussion on Tuning an FI car from Scratch

[Mase]

Well, being that I'm chilling out before this hurricane hits, Ive been looking at this forum in disgust. All it is anymore is people trying to broadcast new products, ask questions that have been answered 184732 times, or just pointless BS. So lets try something new for a chance. This will not be a Hondata vs. AEM EMS vs. Uberdata thread. If it turns into any garbage, it will be deleted. I intend for this thread to be quite informative for those who actually want to learn how to properly tune a FI Motor. I get pm's, im's phone calls (much to my dismay) and all sorts of questions in person about tuning. Frankly, tuning isnt all that hard, Yes i can say that because ive done so many types of cars, stock cars, strict race cars, street warriors, low hp and really high HP. Experience does help, but so does knowledge. We all know that the internet can be a great resource, there is a lot of things I wouldnt know without it. But its seems like there is almost as much good as there is bad now days. Of course everyone has their own way of doing things, some may work better for others. But just because your brothers friend's girlfriends dad says this is so, doesnt mean its true. Lets talk about a few things before we go into detail about actually physically tuning the engine. You must know exactly what the motor needs/does. A boosted car needs different parameters and inputs than an NA car, most notable less ignition timing and a slightly richer mixture. If you want to get into details about why this and that is true. take EFI101, its a great course, and you will learn all sorts of great info. Most tuners I see, they dont really know exactly what they are doing, they just know their buddy ran this amount of timing and this AFR. its not hard to press the + and - keys on the key board, Any 10 year old kid can point out the datalog and connect the dots. Tuning the fuel and ignition curves is not hard. Tuning often is much more than that. it often leads to troubleshooting. why is this car not making the right power it should be. Its extremely hard to know especially if the tuner didnt build the motor, how is he suppose to know if the head has been milled, or if the compression really is 9:1 like the owner says. Its the tuners responsiblity not to listen to the owner lol. he should find out own his own. IE. some things ive seen. the owner of the vehicle already set the timing to 16 degrees. come to find out its way off.... The compression is 9:1. Do a compression test, its more like 10:1. All of this inputs can greatly affect the life of the motor, and the tune for that matter. Ive seen so many people tune cars and never pull the damn plugs, some of the better known tuners to be exact. I dunno if they just forgot, or dont know how to read the plugs. but thats extremely important when tuning an engine. while its hard to tell an exact AFR from reading a plug, you can get a great idea of what timing its running. Just because little johny on HT runs 21 degrees of timing at 20 psi w/ C16 with an 'identical' setup as you, does that mean you should run it too? many times people can get away with it, but its hard for me to justify risking a motor that costs 5k on a hunch or cuz someone else told me. Often what I see is a 'already tuned' map that is total shit. Sure WOT is extremely important, but majority of the map is not WOT. I take a look at peoples maps an i notice a growning trend. Higher rpms means more fuel needed right? well think about this, most cars have higher efficiency at higher rpms then say 2000 rpms. they wont require as much fuel when the motor is more efficient. Some people wont notice how their car is running, but its almost rare to none that i take a map and cant adjust it for the better. Lets take this for example. I tuned an ITB car not too long ago, its already had like 3-4 hours of dyno time. made decent power... over 200 all motor. i put the car on the dyno, and its a pain in the ass, partial throttle is horrible, idling is complete shit. I clean up the idle, it purs like a kitten, clean partial throttle up a bit, but decide to go back to do that later, I do some full throttle pulls, WOT afr is fine, ignition timing is a bit on the high side for my liking. pull a little back, it actually makes a little more power, not much but just a hair, and its running much safer. We start playing w/ partial throttle on the dyno jet, which is hard to do, but the car bucks horribly, and its hard to drive. after a few seconds, i can tell its not the AFR, but by listening to the misfire, i know immediately its the ignition timing. It wants more timing. probably 9 out of 10 people wouldnt know, so the name of the game is, do your homework, gain experience, cuz you will see new stuff all the time that will leave you clueless, unless you know a thing or two about tuning, and mechanics A lot of times, and ive even found myself not making a checklist all the time of what needs to be done before properly tuning a car. Sizing the Injectors, correct spark plugs, gapping, general maint. items, a motor in good shape, correct gas, good drivetrain components, boost controller, no ghetto wiring, etc. Making sure all of these types of situations are taken care of will prevent a wasted day of tuning. I dont know how many times people have brought me a car, ive wasted many hours of my time on it, only to hang it up because something is mechanically or electrically wrong with the car. More discussion to come, ive written enough for now. ill talk about the first steps from starting a fresh basemap, because that seems to be a huge issue, everyone always asks for maps...

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[Boostfed]

Damn good write up! I believe that most of what you posted is dead on TRUE! Unfortunately with the tuning aspects of alot of other tuners.

[Joseph Davis]

Originally Posted by Mase

I get pm's, im's phone calls (much to my dismay)

My voicemail greeting begins something akin to, "Hi, this is Joseph. Please keep in mind that this is my personal line, and not your personal tech support hotline..."

Anyway, I concur. Tuenaring for peak power is gay, troubleshooting is hard. I'm not a tuenarboy so much as I am a fancy-pants diagnostician.

[SYD]

awsome wright up i hope this thread doesnt go to shit..

[Joseph Davis]

Originally Posted by bruceleeroy

awsome wright up i hope this thread doesnt go to shit..

Hyundaidata vs AEM OMG WTF EMS vs Ubercrap pls!

uhm *cough* can we pick a different rep of each tuenar app to go through basemap forming procedures? Seems like a good starting point. With how lengthy the thread will get, probably need to start further topics in new threads.

[Mase]

Originally Posted by J. Davis

Hyundaidata vs AEM OMG WTF EMS vs Ubercrap pls!

uhm *cough* can we pick a different rep of each tuenar app to go through basemap forming procedures? Seems like a good starting point. With how lengthy the thread will get, probably need to start further topics in new threads.

Good idea joseph, but for now, im gonna go for a little ride on the gixxer, i need to ride it and get my fix in before all this shitty weather gets here and wont be able to touch it for awhile....

i wanna see if anyone can add or have any intelligent questions before we go further.

[DD_JonnyLee]

awesome thread, keep it going i want to learn , but every time i look at an ignition table i get all flustered........
-jonny

[FredoSP]

Mase and others .. why dont we develop a standard pre-tuning check list?

[Drew Peacock]

Good thread you said what most should know, so wheres the tech

[IN VTEC]

I'm not sure how basic of an audience you're looking to capture, but if you're hoping to not lose the little people, maybe it would be best if we covered airflow metering first (speed-density in particular, obviously) and how to read a load-rpm map.

I think a listing of general rules of thumb and trends would also be helpful. For example: AFR mixture flame propagation speeds as a function of air:fuel ratio, how VE and torque are related, and how VE affects ignition timing and injector pulse width (and how to correlate it backwards to see high and low VE points). I look at that kind of stuff while tuning to see how the engine is behaving across the powerband.

I also like the terms MBT, RBT, and LBT. Knowing what those terms mean has helped me quite a bit.

The one thing I haven't been able to be certain about is whether or not I can assume that the VE as a function of rpm will always be the same regardless of load. I'm very inclined to say no, but I can't find a firm line of reasoning to support it. If that isn't intuitively understood, I can elaborate on it with a 2D fuel map.

I'm glad you're stepping up to stimulate some good conversation. Hopefully we can all learn a little something from each other, although it's not likely that you'd learn anything worthwhile from me since you're got tons more experience and know-how than I.

[Mase]

Originally Posted by turbozxi

Good thread you said what most should know, so wheres the tech

ok, if you know pretty much everything ive talked about so far.

Do you care to explain why you must run less ignition timing under boost ?

or why in most cases do you need to run more ignition timing w/ higher octane

if you dont know, that is perfectly ok, but most people dont know a lot...

[Mase]

Originally Posted by IN VTEC

I'm not sure how basic of an audience you're looking to capture, but if you're hoping to not lose the little people, maybe it would be best if we covered airflow metering first (speed-density in particular, obviously) and how to read a load-rpm map.

I think a listing of general rules of thumb and trends would also be helpful. For example: AFR mixture flame propagation speeds as a function of air:fuel ratio, how VE and torque are related, and how VE affects ignition timing and injector pulse width (and how to correlate it backwards to see high and low VE points). I look at that kind of stuff while tuning to see how the engine is behaving across the powerband.

I also like the terms MBT, RBT, and LBT. Knowing what those terms mean has helped me quite a bit.

The one thing I haven't been able to be certain about is whether or not I can assume that the VE as a function of rpm will always be the same regardless of load. I'm very inclined to say no, but I can't find a firm line of reasoning to support it. If that isn't intuitively understood, I can elaborate on it with a 2D fuel map.

I'm glad you're stepping up to stimulate some good conversation. Hopefully we can all learn a little something from each other, although it's not likely that you'd learn anything worthwhile from me since you're got tons more experience and know-how than I.

you bring great ideas to the table, however, thats more in detail of the actual motor, and while yes tuning does certainly involve just about everything you have discussed, I dont want to jump into that quite yet, a lot of what you discuss is covered in Ben straders EFI101 class. but it will tie into great detail, so dont go anywhere, im sure even i can learn something from people.

[SSBPGSR]

keep the thread alive! *is interested in learning the art of tuning* i hope this thread doesnt die, it seems to be a great source of knowledge for the people who want to learn, like i do. good writeup and keep more comming

[Drew Peacock]

Originally Posted by Mase

ok, if you know pretty much everything ive talked about so far.

Do you care to explain why you must run less ignition timing under boost ?

or why in most cases do you need to run more ignition timing w/ higher octane

if you dont know, that is perfectly ok, but most people dont know a lot...

Less timing under boost to prevent preigniton caused by excess heat in the combustion chamber preigniting the fuel before it should, with higher octane preignition is not so much a factor as the fuel needs a lot more heat to set it off, hence needing more timing to use it effectively. I was not meaning to be neagtive.

[SYD]

Originally Posted by Mase

ok, if you know pretty much everything ive talked about so far.

Do you care to explain why you must run less ignition timing under boost ?

or why in most cases do you need to run more ignition timing w/ higher octane

if you dont know, that is perfectly ok, but most people dont know a lot...

ok ill take a stab at starting this.. higher octaine requires more timing because of its slower burn rate of the fuel..basically to make this sound as simple as possible igniting the mixture early gives it more time to burn..(because of the slower burn rate) so a complete burn can be made on the power stroke..

[Mase]

Originally Posted by turbozxi

Less timing under boost to prevent preigniton caused by excess heat in the combustion chamber preigniting the fuel before it should, with higher octane preignition is not so much a factor as the fuel needs a lot more heat to set it off, hence needing more timing to use it effectively. I was not meaning to be neagtive.

thats somewhat on target, as boost pressure increases, so does density given a certain area. the combustion time is reduced when u start increasing pressure. You need less time to complete the burn process the higher the boost.

There are tons of topics to discuss, but my main concern is the fact that the EFI101 course covers a lot of this type of stuff, and i no way want to subtract from the opportunity people could take the course....

we'll do our best.

[Drew Peacock]

I like the simple approach!

[Mase]

what we have here is a screen shot of a stock p72 (gsr) map.

If you look, you can see that the rpms increase from top to bottom. you will also notice that hondata uses to different maps for low cam and hi cam (vtec off, and vtec on). AEM only uses one map.

across the top, from left to right, the farthest most portion to the left is the highest vac. then goes over to 0.5 in this map, this would be WOT on NA cars. w/ boosted cars you will have positive load, ie. 5, 10, 12 psi.

different software have different values, can show the load in absolute or atmospheric pressure. as well as different units of pressure. Im used to PSI personally.


As far is the igniton tables are concerned, they display the degree values, on hondatas fuel increments, im honestly not sure if they actually designate anything in particular (i think raw value), but the values in an AEM map can show you the raw value, Pulse width, and duty cycle as well.

Also, with hondata, you can not choose your RPM Break points, w/ AEM you can, this can be helpful, you want the most break points, or greatest resolution so that you can accurately tune more precise.

If you know the motor is only going to rev to 8500. You dont need the fuel map to go up to 11,000 rpms.

Hopefully everyone understands thus far....

[Arturbo]

Finaly a thread worth clicking on in the FI board!! Anyhow I will add this, all to offten I see soooooo many "AFR tuners" as I call them. What people dont realize is that AFR only tells 1/2 the story of what is going on. Its so easy to add or subract fuel at a given load or rpm and make a dyno run. I see that waaaaaaaaaaaaay too much!

Normaly I keep a checklist because I have a really bad memory and its just an outline to follow. Plus I like keeping track of what I did for future reference.

art

[incogNitto]

Originally Posted by Mase

come to find out its way off.... The compression is 9:1. Do a compression test, its more like 10:1.

Just curious...how can you determine an engine's compression ratio from a compression test? If all cylinders test low (but rougly equal), what can cause this and how would you distinguish between this cause and a motor that's supposed to test that way?

[Mase]

Originally Posted by incogNitto

Just curious...how can you determine an engine's compression ratio from a compression test? If all cylinders test low (but rougly equal), what can cause this and how would you distinguish between this cause and a motor that's supposed to test that way?

The best way i tell, i use my own compression tester on all the cars i tuned. I've come to know what PSI is around 9:1, 10:1, and so own...

[TurblowR]

good write up mase. i personally know that mase knows his shit. he tuned my car WOT and partial throttle in like 20 minutes. car still runs like a champ. no knocking and no detonation. idles perfect as well!!

Note: im not trying to say mase tunes quick, but he knows his shit so well he can do it in record time

-Denny

[Mase]

Originally Posted by TurblowR

good write up mase. i personally know that mase knows his shit. he tuned my car WOT and partial throttle in like 20 minutes. car still runs like a champ. no knocking and no detonation. idles perfect as well!!

Note: im not trying to say mase tunes quick, but he knows his shit so well he can do it in record time

-Denny

haha thanks, and mike laskey and I can wrench like pro's while downing many beers and leaving our marks in the street, woot

[SYD]

Originally Posted by Arturbo

Normaly I keep a checklist because I have a really bad memory and its just an outline to follow. Plus I like keeping track of what I did for future reference.

art

a checklist is something i definatley will consider next time, backtracking is a bitch!!

[Mase]

Ill come up w/ a checklist sometime soon